Electrodepositing method and apparatus



Oct- 6, 1925- I 1,555,866 v w. w. M CORD Filed OOE. 24. 1924 Patented Oct. 6, 1925.

1,555,866 PATENT OFFICE. I

WILLIAM W. MOCORD, OF WYANDOTTE, MICHIGAN, ASSIGNOR TO MoCORD RADIATOR & MFG. ('30., 0F DETROIT, MICHIGAN, A CORPORATION OF MAINE.

ELECTRODEPOSITING METHOD AND APPARATUS.

Application filed October 24, 1924. Serial No. 745,576.

To all whom it concern:

Be it known that I, WILLIAM W. MoCoRD, a citizen of the United States, residing at Wyandotte, in the county of Wayne and State of Michigan, have invented new and useful Improvements in Electrodepositing Methods and Apparatus, of which the following is a specification.

In the making of sheet copper, sheet nickel, or other metal sheet electrolytically, the outside edges of the sheet on the cathode have always been a source of trouble in the stripping of the sheet. These edges have been formed in various ways. A portion of the cathode along the edges has been painted with various non-conductive compounds, most of them with an asphaltum base; compressible material, such as rubber. has either been butted up to the extreme edges of the cathode under pressure or held under pressure along each edge; various non-conductive materials have been stuck or cemented along the .edges of the cathode face to cover a portion of it, etc. The purpose in all cases was the same; i. e. to form a straight line along or near the edge of the cathode, be-

tween the conductive face of the cathode and some non-conductor.

The results have been poor in all cases for two reasons. It is extremely difficult to secure an absolute joint in the beginning between the cathode face, which is curved usually. and the nonconductive material. But even it it is once secured. it cannot be maintained for any great length of time. No matter what material is used, the acid content of the "lectrolytic bath works on it until tiny openings are formed between the cathode face and the non-conductor. As soon as these are made. depos tion occurs in them which has the effect of giving the sheet tiny tentacles extending out from the sheet into the space between the cathode face and the non-conductor. This makes the sheet P stick in stripping so that it does not come away from the cathode readily.

The sheet may strip several times, tearing along the edge about where the line of the non-conductor was supposed tobe, but in these cases the tentacles are left and build up heavier each time, gradually extending outward over the cathode face in irregular shapes until the sheet in stripping tends to tear away from them at various angles, leaving large sections of sheet adhering to the cathode, and perhaps tearing clear across the sheet on an angle. When the sheet is strlpped by hand, this is a constant source of annoyance, loss of material and time, and these tentacles have to be repeatedly and extremely carefully removed very often or the non-conductive material entirely removed and replaced with other, necessitatmg quite a loss in time. Furthermore, it is an almost absolute ban to automatic stripping.

In accordance with my invention, I con-v trol the amount of electric current reaching the cathode along the edge to be defined, and thus define the edge by lessening the amount of the deposit on the cathode at such edge. One way to carry this out is to place a band of metal in front of the cathode face but not touching it, in such a way as to form a shield over a strip of about one-half inch in width. A gap or opening of approximately one-sixteenth of an inch is left between the cathode face and the shield. The shield is electrically connected to the ne ative pole of the generator in any suitable manner, so' as to form a cathode in addition to the main cathode but with the distinction that the path of least resistance to the current coming from the electrolyte in the immediate vicinity of the shield is through the shield and not through the main cathode. This has the effect of diverting the current in the immediate vicinity of the shield away from the cathode face and through the shield, so that little if any deposit occurs on the cathode face under the shield and this little for only a very short distance, the edges of the cathode face being entirely free of deposit. This little deposit under the edge of the shield is of much lighter gauge than that on the main body of the cathode face and gives readily to pass out from under the shield and, having no more grip on the cathode face than elsewhere due to the opening under the shield with nothing to hold it down, strips as readily here as elsewhere. i

This structure is illustrated in the accompanying drawings, in which- Fig. 1 is a vertical sectional view of the apparatus;

Fig. 2 is a top plan view of the same; and

Fig 3 is an enlarged fragmentary vertical sectional view taken on line 3-3 of Fig. 2. I

This apparatus includes a tank 1 containing an electrolyte 2, in which revolves a drum 3 on a shaft 4. The drum and shaft are arranged to turn about a vertical axis.

Anodes 5, 5 extend into the electrolyte in the space between the drum and the upright wall of the'tank. Conductors or wires 6 connect the anodes with the positive pole of the'generator (not shown) and supply current to the electrolyte.

The cathode face 7 of the drum-is lead, and over each marginal portion thereof is a shield 8, spaced outward from the cathode face to provide a gap or opening therebetween, as mentioned heretofore. These shields are preferably formed from one iece of metal carried on'thedrum 3 directly ack of and in contact with the lead cathode 7. The shields 8 are the bent over margins of the plate, as shown. Conductors or wires 9, 9 connect the shields. with the negative pole of the 7 generator.

.- Current passes through the electrolyte? to the cathode 7 in straight lines, as indicated by the arrows in Fig. 1. A metal deposit 10 is formed in the cathode 7. This deposit is even in thickness. everywhere except under the shields 8, where it thins out, due to the fact that the current chooses the path of least resistance and is diverted to the shields 8, passing out through them without going through the cathode 7. It will be noted from Fig. 3 that the deposit 10 does not extend to the outside edges of the cathode 7, and it is important that shields 8 far enough overlap the cathode 7 to accomplish this purpose. The current which directly strikes cathode 7 passes through it,

through the shield plate beneath it, and

back to the generator by conductors 9.

The success of the apparatus is dependent upon making the shields 8 a path of lesser resistance to the current in its immediate vicinity than the cathode 7 To accomplishthis, the shields 8 are preferably made of aluminum, this being a metal possessin higher conducting properties than the lea of the cathode 7.

The, deposited sheet is readily strippable along its edges, because ithas been thinned out there and has nothing to prevent its strlpping. This is due primarily to the fact that lead is a relatively poor conductor and is shielded along the edges by a better conductor. Other conductors could of course be used for either the cathode 7 or the shields 8 or the same metal used for both, the difference in resistance being accomplished by artificially increasing the. resistance in the electrical returns from the cathode 7 as opposed tothe shields 8.

By arranging the drum 3 to be rotated about a vertical axis, the entire circumference of the drum may be submer ed in the electrolyte 2, instead of only half the same as when the drum is arranged to revolve about a horizontal axis.

The drum is supported in the electrolyte 111 any suitable manner and any suitable mechanism (notshown) may be employed for raising the drum out of the tank, as when it is desired to strip the deposited sheet'therefrom.

, My invention is susceptible to various forms, so I do not wish to be limited to the particular form shown and described.

I claim as my invention:

1. The method of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in lessening the amount of the deposit along the edge of the sheet.

2. The method of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in controlling the amount of electric current reaching the cathode along the edge of the sheet to lessen the amount of the deposit on the cathode along such edge.

3. The method of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in diverting the electric current from the cathode in advance thereof along the edge of the sheet to lessen the amount of the 'deposit on the cathode at such edge.

4. The method of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in interposing a shield of conductive'material in front vof the cathode and spaced outward therefrom along the' portion of the cathode at such edge to lessen the amount of the deposit on the portion of the cathode behind the shield.

5. The method. of lesseningthe amount of deposit on a predetermined portion of a cathode in an electro-depositing apparatus,

which consists in interposing a shield of con- Thus twice the de-' .positing surface of the drum is secured.

along such edge by providing a path of lesser resistance to the electric current in advance of the cathode along such edge than is provided through the cathode.

7. The method of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in interposing a shield of conductive material in front of the cathode and spaced outward along the portion of the cathode at such edge to provide through the shield a path of the cathode behind the shield and having the shield of a material of a higher conductivity than the cathode to lessen the amount of the deposit on the cathode behind the shield.

9. Themethod of defining an edge on an electrolytically deposited metallic sheet during the deposition thereof, which consists in depositing the sheet on a cathode face of lead and placing a shield of aluminum in 'front of the cathode and spaced outward therefrom along such edge with the shield connected with the negative side of the apparatus circuit.

10. In an electro-depositing apparatus, the combination with a cathode for the deposition of a metallic sheet thereon, of means for controlling the amount of electric current reaching the cathode along the edge of the sheet for defining such edge during the deposition of the sheet.

11. In an electro-depositing apparatus, the combination with a cathode for the deposition of a metallic sheet thereon, of means for diverting the electric current from the cathode in advance thereof along the edge of the sheet for defining such edge during the deposition of the sheet.

12. In an electro-depositing apparatus, the combination with a cathode for the deposition of a metallic sheet thereon, of a shield of conductive material in front of a portion of the cathode and spaced outward therefrom, said shield being connected with the negative side of the apparatus circuit.

13.'In an electro-depositing apparatus,

the combination with a cathode for the deposition of a metallic sheet thereon, of shields of conductive -material along the opposite edges of the cathode and spaced outward therefrom to define the edges of the sheet deposited on the cathode, said shields being a connected with the negative side of the apparatus circuit.

14. In an electro-depositing apparatus, the combination with a drum, of a cathode face thereon, and shields of conductive material in front of the edges of said cathode and spaced outward therefrom, said shields being carried by said drum and having contact with the cathode face behind the same.

15. In an electro-depositing apparatus, the combination with a drum, of a cathode face thereon, and shields ofconductive material in front of the edges of said cathode and spaced outward therefrom, saidshields being carried by said drum and formed by the bent over marginal portions of a plate in contact with the rear side of the cathode.

16. In an electro-depositing apparatus, the combination with a cathode for the deposition of a metallic sheet thereon, of a shield of conductive material in front of a portion of the cathode and spaced outward therefrom, said shield being made of a metal of higher conductivity than the cathode and connected with the negative side of the apparatus'circuit. 7 1 17. In an*- electro-depositing apparatus, the combination with a tank, of a drum arranged in said tank for rotation about a vertical axis,v a lead cathode face on the cylindrical surface of said drum, and an aluminum plate on the same surface of the drum behind and in contact with said cathode, 

